A couple of i915_audio_component ops have been added and accessed
directly from patch_hdmi.c.  Ideally all these should be factored out
into hdac_i915.c.

This patch does it, adds two new helper functions for setting N/CTS
and fetching ELD bytes.  One bonus is that the hackish widget vs port
mapping is also moved to hdac_i915.c, so that it can be fixed /
enhanced more cleanly.
Reviewed-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>